Manufacture of artificial silk and the like



March 9, 1937. H. w. WEBB MANUFACTURE OF ARTIFICIAL SILK AND THE LIKE.

Filed Nov. 3, 1932 Patented Mar. 9, 1937 UNITED STATES PATENT OFFICE MANUFACTURE OF ARTIFICIAL SILK AND THE LIKE 11 Claims.

My invention relates to improvements in orifices of tapered and/or tortuous bore for spinnerets for the extrusion of artificial silk and similarly produced filamentary products, to means and apparatus for and methods of producing such orifices in spinnerets, to new and improved arrangements and alignments of tortuous spinneret bores of opposite hands or like hands of rotation in the multiple bored spinneret and/or various cross section at the plane of emergence of the extruded material, and to novel and valuable improved textile products as to physical characteristics which are formed by extrusion through such bores in such arrangement and alignment.

My invention has as its objectives; the formation of tapered and/or tortuous orifices of predetermined size, arrangement and cross-section at various planes in spinnerets in a fashion to be readily produced and cleaned, the arrangement and alignment thereof to efiect bundling and cabling of the emergent tortuous filamentary prodnot by the interlinking and/or separating contour of contiguous filaments to afiord predetermined textile characteristics, and the new textile 25 product so effected.

30 means of producing in an expeditious and economical manner and will show how they are arranged and aligned in a multiple jet spinneret to produce a new textile product. My invention is particularly adapted to be used with those types of extrusion material which set immediately on emergence such as viscose or rubber latex expressed into a coagulating agent, though it is not limited thereto. While the apertures used for artificial silk of ordinary denier are very small being ordinarily .0035" in diameter I have found it readily possible to produce apertures of equivalent and even smaller area with predetermined cross-section, with swirl channels debouching into them of 100 to 1 inch in pitch. The form of bore which I preferably employ in the present invention is such that the cast made from it appears like the frustrum of a conical or pyramidal body twisted about its longitudinal axis The cast may be considered a conical frustrum with one or more spiral flutes whose pitch is uniform, preferably, along the axis of the cone and which deepen as they approach the small end. In the limiting case of one flute it somewhat resembles a wood screw, and with multiple grooves, a twistedpyramid withtop cut off and incurved sides.

Further, the cast is preferably produced as a conical frustrum of steeper or more acute angle with the axis as it nears the top or small end, approaching a cylindrical form. The bore is formed with a spirally grooved taper punch by displacement of the metal of a spinneret wall, the operative zone of the punch being like the bore cast above described. The punch is preferably of tungsten or other tough alloy steel and is provided with depressions or grooves at its tapered point, one or more in number, by cutting, grinding or embcssing. These grooves preferably increase in depth as they near the point, in order to facilitate flow through the orifice formed and cleaning of the bore. They must be so formed as to permit ease of retraction of the punch, and that they may displace the metal penetrated with minimum stress, particularly when propelled and retracted by rotation with a screw, I preferably form the fiuting of a spiral pitch uniform along the axis of the punch, except for the case to be later described. Uniformity of pitch along the axis decreases the angle of inclination of the fiute to axial planes as the end of the taper punch is approached. This angle becomes about 45 degrees with pitch of 100 to 1 inch at a diameter of .003. This is about the limit of turns to the inch at this diameter without impeding extrusion fiow as with more turns the angle would be more obtuse. Cross-section of bore is determined by the shape of the flute but becomes a greater variation from the circle or regular polygon basal section as the [sectioning plane nears the tip, but at the extreme tip the cross-section may remain constant for a very short distance to assure uniformity in removing burr.

As it is desirable for purposes of cabling, the product of a multiple jet spinneret that contiguous filaments should mesh and interlink by reason of their opposite hands of twist effected in extrusion as exemplified in the above mentioned co-pending application, so it is likewise desirable in other cases to form all the filaments of a strand of one hand that the surface may mesh with a similar strand likewise formed of filaments of the opposite hand. Such a combination of strands formed of and interlinking by the superficial structure of the filaments of contiguous strands is believed to be new in the art. It is also desirable in some cases to separate the filaments to secure good dyeing and processing characteristics, in which case I employ the same hand of rotation throughout the strand. To produce filament having a tendency to curl it is necessary that the filament be unsymmetrical in section. By punching the tortuous orifice with a single flute or unsymmetrical fiuting, as for instance by two flutes 120 degrees apart with the third flute that would make a symmetrical fluted 3 fiute punch left out, I produce a filament having such a tendency to curl, by reason of or when subjected to internal strains.

The present invention may be considered an improvement upon the one described in the copending application in that it renders possible the production of swirl channels in the extrusion orifice of finer pitch up to the desideratum and of greater depth with enhanced ease and accuracy. It is more easily cleaned and less resistant to flow. Attaining its final cross-section at the plane of greatest velocity it has less tendency to lose the filament shape before setting when subjected to stretch at the extrusion point. Filament made by the present invention shows the number of twists per inch indicated by the pitch of the swirl channel less the percentage by which the filament is stretched. For instance with a pitch of 32 to the inch in the orifice and a stretch of the filament shows 16 to the inch. Hence it is de sirable in case the interlinking or the spacing quality of the product is to be increased beyond the point where the number of turns of extrusion twist of the filament will sufiice, to provide additional protrusions. This is accomplished according to the present invention by increasing the number of flutes while the pitch remains the same. It is likewise part of my invention that multiple flutes or their equivalent in the extruded filament shall furnish contraction starting lines along which the surface of a filament whose surface sets sooner than its interior, may contract in a predetermined manner both in stretching, dyeing, drying and processing generally. The contraction of a Chinese lantern will indicate What this phase of my invention accomplishes. That the section plane of final shape in the bore be close to or coincide with the exit plane and the zone of greatest velocity in extrusion to accomplish this, is part of my invention, as is the product so formed. I do not limit myself to tor tuous channels in the bore of the spinneret orifice in putting into effect this part of the present invention, for they may for this purpose be parallel to the axis of the bore. Viscose silk is an example of such a filament. In the case just mentioned or where the fiuting is of relatively steep pitch and rotation in penetration of the spinneret wall does not exceed about one-third of a turn, I have found it possible to force in and withdraw the punch directly allowing the fiuting to direct the travel and/or rotation of the punch. Frictionless bearings such as ball bearings are necessary for both thrust and retraction if the punch rotates. I prefer, however, to employ screw propulsion and retraction applied to the punch without backlash where the punch rotates. It is essential that the fiuting clear as retraction starts.

In the drawing Figure 1 represents a spinneret wall sectioned to show a bore with double swirl channel. Figure 2 represents a spinneret wall sectioned to show a bore with single swirl channel. It will be noted how, though the pitch of the swirl channels is uniform along the axis of the bore, the angle with planes through and inclusive of the axis becomes more acute as the bore exit is approached. Figure 3 represents the shape of the bore exit as it would appear if viewed from beneath in the case of the bore sectioned in Fig. 1 and Figure 4 represents the corresponding shape of the single swirl channel bore sectioned in Fig. 2. Figure 5 represents diagrammatically a punch a of right hand fiuting penetrating the sectioned spinneret wall c and propelled by a screw in the sectioned housing b. Fig. 6 shows in cross section a portion of a spinneret formed in accordance with my invention with three filaments posited therein as in process of extrusion, the middle filament being of right hand and the adjoining filaments of left hand, as herein described.

Having described and set forth my invention, what I claim is:

1, In a multiple hole spinneret, a plurality of tapered, rifled holes with bores of opposing hand adjoining, all the holes of either hand being substantially identical in size and form with the other holes of that hand.

2. A multiple hole spinneret having a plurality of tapered, rifled extrusion orifices, the rifiing of some orifices being of opposite hand to that of other orifices.

3. A spinneret plate having an extrusion orifice substantially circular at the pressure face, the bore of the orifice having progressively diminishing cross-section and terminating in a non-circular exit.

4. Structure as set forth in claim 3, the bore being spirally fluted.

5. Structure as set forth in claim 3, the bore being spirally fluted, the fiuting being of substantially uniform pitch.

6. A spinneret plate having an extrusion orifice tapered to a plane near the exit and having a swirl channel formed in the walls of the orifice in the tapered zone.

7. A spinneret plate having an extrusion orifice tapered to a non-circular exit and fluted along the bore of the orifice, the fiuting extending spirally around the bore, the cross-section of the bore decreasing in circularity from pressure plane to exit.

8. A bundle of tortuous filaments, the filaments being non-circular and the tortuousity of some filaments being of opposite hand to that of contiguous filaments, the filaments being stabilized in their tortuousity.

9. A tortuous organic filament of substantially uniform non-circular cross section, the tortuousity being regular in pitch as measured along the axis of the filament and stabilized.

10. A bundle of tortuous extruded organic filaments of substantially uniform cross section both as to sections through each individual and as to the several filaments, the said cross sections being non-circular; the tortuousity of adjoining fila ments being of opposite hand and stabilized.

11. An extruded filament having a tendency to remain curled, said filament being of tortuous form, non-circular and non-symmetrical in cross section, and set in tortuous form.

HARTWELL WILLIAM WEBB. 

